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The regulation and administration of aviation within this country is greatly influenced by a core set of beliefs concerning the safety of aircraft and their operation. This core set of beliefs is referred to as the ontology of aviation safety because it is grounded in a particular reference to reality. The ontology of aviation safety is founded upon the beliefs that aviation operations are either "safe" or "unsafe", that accidents ore preventable, and that if accidents happen then culpability is attributable. These core beliefs support and objectified/reified view of safety which represents a particular reality. Language, more than any other attribute, separates man from other animals. It is through language that man communicates his most profound feelings and ideas. A very basic premise of this dissertation is that language usage reflects beliefs and values. The use of the terms "safe" and "unsafe" when referring to aircraft operations represents the belief that "safe" is an attainable state, in other words, it represents an objectified/reified view of aviation safety. A hermeneutic interpretive approach was used to examine language use within various aviation texts to include: newspaper articles, speeches by Federal Aviation Administration (FAA) officials, testimony by FAA officials before Congress, and selected books concerning aviation safety. By referring to aviation operations as either "safe" or "unsafe" in discourse and dialogue, an objectified/reified view of aviation safety is subtly perpetuated. This view is deeply rooted in the Amierican concept of aviation safety. / Ph. D.

The National Transportation Safety Board has cited deficiencies in judgement and decision-making as contributing factors in numerous general aviation accidents. Several studies have also indicated that some pilots exhibit <i>hazardous attitudes</i> in their decision-making processes. Although decision-making and judgment training is mentioned by the Federal Aviation Administration as areas that should be taught to aspiring pilots, there are relatively few current guidelines to assist flight or ground school instructors. This study centers on the decision-making characteristics of expert and novice pilots. Four expert and four novice pilots were selected by the researcher. All of the subjects were interviewed about their decision-making processes as they related to four aeronautical decision-making scenarios. Experts exhibited characteristics and themes that differed noticeably from that of the novices. One of the more pertinent differences involved what some writers have referred to as <i>cognitive maps</i>. These mental guides appeared to be used effectively by experts in attempting to cope with problems associated with the scenarios. Novices also appeared to make use of cognitive maps in their decision-making processes. Their maps, however, were primitive in comparison to the experts and resulted in difficulties when attempting to address specific scenarios. The findings regarding the decision-making thought processes of experts were consistent with previous studies (e.g., decisions were based on pertinent mental cues from their experiences). The findings related to novices revealed five themes that included: a. the quantity and quality of information acquired to assess risk was often deficient; b. the interpretation of the risks associated with each scenario reflected a lack of attention to pertinent issues related to the scenarios; c. decision-making was often based on recognition of familiar conditions with which novice subjects could relate; d. decision-making often reflected an emphasis on rules and procedures that novices had been taught or acquired through independent research and e. novices exhibited hazardous attitudes in their decision-making processes. The researcher reviewed significant findings and areas in need of further research. A brief conclusion and recommendations conclude the study. / Ph. D.

Aviation suffers many delays due to the lack of timely air traffic flow management. These delays are also caused by the uncertainty weather information; and the lack of efficient dissemination of weather products to pilots. It is clear that better models are needed to quantify air traffic flow in three flight regions - en-route, in the terminal, and on the ground, to determine aviation weather information requirements at each region, and to quantify their bandwidth requirements. Furthermore, the results from those models can be used to select alternative future aviation communication systems. In this research, the 'ITHINK' and 'MATLAB' software packages have been used to develop a lumped Air Traffic Flow Model (ATFM) and an Aviation Weather Information and Bandwidth Requirements Model (AWINBRM). The ATFM model is used to quantify the volume of air traffic in each phase of flight in three flight regions. This model can be used to study navigation, surveillance, and communication requirements. The AWINBRM model is used to study aviation weather information requirements in different flight phases of flight. Existing and potential communication systems used for transmitting aviation weather information are explored in this research. Finally, a usable and practical computer model - Aircraft Impacted and Detour Model (AIDM) around an aviation weather system is developed. This model is used to compare the costs between detoured flights around a weather system and delayed flights at the airports. The purpose of this research is to study air traffic flow and aviation weather information and bandwidth requirements through modeling. The ultimate goal of the models described here is to serve as a living laboratory where policies can be tried before implementing them into the real system. Moreover, these computer models can evolve dynamically through time allowing decision makers to exercise policies at various points in time to quantify results with ease. This research would be a first integrated model for combing air traffic flow and aviation weather requirements and determining the quantity of aviation weather information between pilot and ground service centers. This research would be a guideline for aviation industry to build an efficient and timely aviation weather information transmission system with minimum budget. Consequently, this research will reduce aviation delays and improve aviation safety. / Ph. D.

This study seeks to investigate weather-related flight delay trends at 13 United States airports. Flight delay data were collected from 2004-2019 and normalized by airport operations data. Using Support Vector Regression (SVR), visual trends were identified. Further analysis was conducted by comparing all four meteorological seasons through computing 95% bootstrap confidence intervals on their means. Finally, precipitation and snowfall data were correlated with normalized delays to investigate how they are related. This study found that the season with the highest normalized delay values is heavily dependent upon location. Most airports saw a decrease in the SVR line at some point since 2004, but have since leveled off. It was also discovered that while precipitation trends are not changing drastically, delay variability has decreased at many airports in the last 10 years, which may be indicative of more effective mitigation strategies.

This research aims to analyze the spatial and temporal characteristics of instrument meteorological conditions (IMC) over the Southern Appalachian Region from 2008 to 2023, utilizing Meteorological Terminal Aerodrome Report (METAR) stations across six USGS-defined physiographical provinces. IMC is defined as visibility less than three statute miles and/or cloud ceiling heights less than 1,000 feet above ground. Percentage of hours reporting IMC are considered on an annual, seasonal, and hourly basis. The greatest increase in IMC over the period occurs in the Piedmont province, and the greatest decrease in the Interior Low Plateaus province. All provinces experience the greatest amount of IMC in wintertime, and the season with the fewest IMC hours varies by province. All provinces see a maximum hour of IMC within three hours following sunrise except summertime in the Interior Low Plateaus, which experiences the highest frequency of IMC within two hours prior to sunset.

Doctor of Philosophy / Department of Special Education, Counseling and Student Affairs / Fred O. Bradley / Over the last few years, the safety record of U.S. commercial airlines has improved to the point where the statistics on accidents are negligible. The overwhelming numbers of aviation fatalities occur in General Aviation (GA) accidents. While the fatal accident rate has improved—from around 5.0 per 100,000 miles flown in the post–World War II era to varying between 1.2 and 1.5 since 1996—it still results in 450 to 700 deaths per year. In 2013, improving GA safety was on the National Transportation Safety Board’s (NTSB’s) most wanted list. The NTSB has cited a lack of aeronautical knowledge as the cause of many of these accidents. If pilots are required to pass Federal Aviation Administration (FAA) knowledge and practical tests prior to obtaining a new pilot certificate, how could they not possess the knowledge needed to operate in the National Airspace System (NAS)? Some, attributing it to a failure to learn basic aeronautical knowledge, are concerned that potential pilots memorize the answers to test questions published in commercially available test guides and quickly forget the material after passing the test. The purpose of this retrospective causal comparative study was to see if airman knowledge tests scores are related to fatal accidents. Fatal GA accidents that had pilot error as a causal factor were compared with those in which maintenance factors caused the accidents, to see if there were significant differences in the pilots’ knowledge test scores. The time that potential pilots took to answer skill-based questions that required calculation or interpretation was compared to the time to answer recall questions to see if rote memorization may have been involved in passing the knowledge test. The results of this paper may have implications on how AFS 630 structures the FAA knowledge tests and how instructors prepare potential pilots for these tests.

There exists no predefined framework for aviation policy making and development. While aviation policy planning in most developed countries comes as a result of institutional and industry coordination and is embedded within other national policies addressing the welfare and growth of the country, it is found that in many cases in less developed countries (LDCs), aviation policy planning is often influenced by political pressures and the interests of fund donors. The complexity of this situation in the developing countries results in aviation plans that represent stand alone studies and attempt to find solutions to specific problems rather than comprehensive aviation plans which fit well the country‘s competitiveness profile and are properly coordinated with other national policies for achieving medium and long-term objectives. This study provides a three-stage policy development framework for aviation strategic planning based on situational analysis and performance benchmarking practices in order to assemble policy elements and produce a best-fit aviation strategy. The framework builds on study results that indicate an association between air transport sector performance and aviation policy strategies, arguing that it is not sufficient to simply describe performance but also to be able to assess it and understand how policymakers can use strategic planning tools to affect the air transport industry efficiency levels. This can be achieved by recognizing the level of the country‘s stage of development and working on enhancing the policy elements that produce better output and induce more contributions by aviation to the national economic development and connectivity levels. The proposed aviation policy development framework is systematic and continuous. It helps policymakers in LDC to manage uncertainty in complex situations by allowing them to defend, correct and re-examine the policy actions based on a forward thinking approach which incorporates the contingency elements of the policy and tracks the developments that can affect the odds of its success. The framework‘s elements and its flow of process are explained by providing an illustrative example applied to the Hashemite Kingdom of Jordan.

Approved for public release, distribution is unlimited / The purpose of this study is to investigate U.S. Naval Academy student predictors of aviation selection for graduates between 1995 and 2002. The main hypothesis is that the background characteristics that predict aviation selectees will differ from the characteristics that predict non-aviation selectees. Although prior research suggests that several characteristics (academic, cognitive, athletic, and personality traits) play an important role in predicting success in aviation, other research suggests that many of those characteristics have not been included in the service selection process at the Naval Academy. Two empirical models were estimated to investigate this hypothesis. The models were used to determine whether the significance of predictive factors differ between all aviation selectees and non-aviation selectees, and likewise between pilot aviation selectees and non-pilot aviation selectees. The results show that of all of the variables in both models PFAR (an ASTB score) was the most important factor in predicting aviation selection. Both PFAR and academic grade point average at USNA had a large impact on aviation selection and separately on pilot selection. These results were representative of both aviation and pilot selection. It is also important to note that some variables were strong negative predictors in the models, although prior research suggested they would be positive predictors of aviation success. Apparently, the factors that predict success in aviation flight training are not the same that predict selection of the aviation community. / Lieutenant, United States Navy

Actuellement, on constate dans le domaine de la navigation, un besoin croissant de localisation par satellites. Apres une course a l'amelioration de la precision (maintenant proche de quelques centimetres grace a des techniques de lever d'ambiguite sur des mesures de phase), la releve du nouveau defi de l'amelioration de l'integrite du GNSS (GPS, Galileo) est a present engagee. L'integrite represente le degre de confiance que l'on peut placer dans l'exactitude des informations fournies par le systeme, ainsi que la capacite a avertir l'utilisateur d'un dysfonctionnement du GNSS dans un delai raisonnable. Le concept d'integrite du GNSS multi-constellation necessite une coordination au niveau de l'architecture des futurs recepteurs combines (GPS-Galileo). Le fonctionnement d'un tel recepteur dans le cas de passage du systeme multi-constellation en mode degrade est un probleme tres important pour l'integrite de navigation. Cette these se focalise sur les problemes lies a la navigation aeronautique multiconstellation et multi-systeme GNSS. En particulier, les conditions de fourniture de solution de navigation integre sont evaluees durant la phase d'approche APV I (avec guidage vertical). En disposant du GPS existant, du systeme Galileo et d'un systeme complementaire geostationnaire (SBAS), dont les satellites emettent sur des frequences aeronautiques en bande ARNS, la question fondamentale est comment tirer tous les benefices d'un tel systeme multi-constellation pour un recepteur embarque a bord d'un avion civil. En particulier, la question du maintien du niveau de performance durant cette phase de vol APV, en termes de precision, continuite, integrite et disponibilite, lorsque l'une des composantes du systeme est degradee ou perdu, doit etre resolue. L'objectif de ce travail de these est donc d'etudier la capacite d'un recepteur combine avionique d'effectuer la tache de reconfiguration de l'algorithme de traitement apres l'apparition de pannes ou d'interferences dans une partie du systeme GNSS multiconstellation et d'emettre un signal d'alarme dans le cas ou les performances de la partie du systeme non contaminee ne sont pas suffisantes pour continuer l'operation en cours en respectant les exigences de l'aviation civile. Egalement, l'objectif de ce travail est d'etudier les methodes associees a l'execution de cette reconfiguration pour garantir l'utilisation de la partie du systeme GNSS multi-constellation non contaminee dans les meilleures conditions. Cette etude a donc un interet pour les constructeurs des futurs recepteurs avioniques multiconstellation. / The International Civil Aviation Organization (ICAO) has defined the concept of Global Navigation Satellite System (GNSS), which corresponds to the set of systems allowing to perform satellite-based navigation while fulfilling ICAO requirements. The US Global Positioning Sysem (GPS) is a satellite-based navigation system which constitutes one of the components of the GNSS. Currently, this system broadcasts a civil signal, called L1 C/A, within an Aeronautical Radio Navigation Services (ARNS) band. The GPS is being modernized and will broadcast two new civil signals: L2C (not in an ARNS band) and L5 in another ARNS band. Galileo is the European counterpart of GPS. It will broadcast three signals in an ARNS band: Galileo E1 OS (Open Service) will be transmitted in the GPS L1 frequency band and Galileo E5a and E5b will be broadcasted in the same 960-1215 MHz ARNS band than that of GPS L5. GPS L5 and Galileo E1, E5a, E5b components are expected to provide operational benefits for civil aviation use. However, civil aviation requirements are very stringent and up to now, the bare systems alone cannot be used as a means of navigation. For instance, the GPS standalone does not implement sufficient integrity monitoring. Therefore, in order to ensure the levels of performance required by civil aviation in terms of accuracy, integrity, continuity of service and availability, ICAO standards define different systems/algorithms to augment the basic constellations. GPS, Galileo and the augmentation systems could be combined to comply with the ICAO requirements and complete the lack of GPS or Galileo standalone performance. In order to take benefits of new GNSS signals, and to provide the service level required by the ICAO, the architecture of future combined GNSS receivers must be standardized. The European Organization for Civil Aviation Equipment (EUROCAE) Working Group 62, which is in charge of Galileo standardization for civil aviation in Europe, proposes new combined receivers architectures, in coordination with the Radio Technical Commission for Aeronautics (RTCA). The main objective of this thesis is to contribute to the efforts made by the WG 62 by providing inputs necessary to build future receivers architecture to take benefits of GPS, Galileo and augmentation systems. In this report, we propose some key elements of the combined receivers' architecture to comply with approach phases of flight requirements. In case of perturbation preventing one of the needed GNSS components to meet a phase of flight required performance, it is necessary to be able to switch to another available component in order to try to maintain if possible the level of performance in terms of continuity, integrity, availability and accuracy. That is why future combined receivers must be capable of detecting the impact of perturbations that may lead to the loss of one GNSS component, in order to be able to initiate a switch. These perturbations are mainly atmospheric disturbances, interferences and multipath. In this thesis we focus on the particular cases of interferences and ionosphere perturbations. The interferences are among the most feared events in civil aviation use of GNSS. Detection, estimation and removal of the effect of interference on GNSS signals remain open issues and may affect pseudorange measurements accuracy, as well as integrity, continuity and availability of these measurements. In literature, many different interference detection algorithms have been proposed, at the receiver antenna level, at the front-end level. Detection within tracking loops is not widely studied to our knowledge. That is why, in this thesis, we address the problem of interference detection at the correlators outputs. The particular case of CW interferences detection on the GPS L1 C/A and Galileo E1 OS signals processing is proposed. Nominal dual frequency measurements provide a good estimation of ionospheric delay. In addition, the combination of GPS or GALILEO navigation signals processing at the receiver level is expected to provide important improvements for civil aviation. It could, potentially with augmentations, provide better accuracy and availability of ionospheric correction measurements. Indeed, GPS users will be able to combine GPS L1 and L5 frequencies, and future GALILEO E1 and E5 signals will bring their contribution. However, if affected by a Radio Frequency Interference, a receiver can lose one or more frequencies leading to the use of only one frequency to estimate the ionospheric code delay. Therefore, it is felt by the authors as an important task to investigate techniques aimed at sustaining multi-frequency performance when a multi constellation receiver installed in an aircraft is suddenly affected by radiofrequency interference, during critical phases of flight. This problem is identified for instance in [NATS, 2003]. Consequently, in this thesis, we investigate techniques to maintain dual frequency performances when a frequency is lost (L1 C/A or E1 OS for instance) after an interference occurrence.